A former North Korean diplomat, Thae Yong Ho, outlined his assessment of why Kim Jong Un has been adamant in his pursuit of a nuclear-tipped inter-Continental Ballistic Missile (ICBM), during a speech in Washington D.C. on Tuesday.

Speaking at the Center for Strategic and International Studies (CSIS), Thae – who defected to South Korea in mid-2016 from the North Korean Embassy in the UK – outlined four key reasons for what he called Kim’s “obsession” to develop such capabilities.

These included Kim’s lack of initial legitimacy when first assuming power, inherent risks in pursuing economic reforms, concerns with the military